2 MonadLib

It is a new version of the mtl package with transformers: ReaderT WriterT StateT ExceptT SearchT ContT

It also defines BaseM which is like MonadBase above.

3 LazyWriterT

This came up on the mailing list: Why is WriterT never lazy? The answer is it does not use lazy patterns with "~". So here is a more useful New monads/LazyWriterT that add two "~" to the definition of (>>=) and renames WriterT to LazyWriterT.

4 MonadRandom

A simple monad transformer to allow computations in the transformed monad to generate random values.

5 MonadSupply

Here is a simple monad/monad transformer for computations which consume values from a (finite or infinite) supply. Note that due to pattern matching, running out of supply in a non-MonadZero monad will cause an error.